13 light Flashcards
Laws of Reflection
- The incident ray, reflected ray and normal at the point of incidence all lie on the same plane.
- The angle of incidence, i, is equal to the angle of reflection, r.
Characteristics of Reflected Image
- Virtual
- Upright
- Same size
- Laterally inverted
- Equal distance between the plane and image
Laws of Refraction
- The incident ray, refracted ray and normal at the point of incidence all lie on the same plane.
- For two given media, the ratio sin i/ sin r is a constant where i is the angle of incidence and r is the angle of refraction.
Formula
Refractive Index
n = sin i/ sin r
n = c/ v
n = 1/ sin c
Formula
Refractive Index
Depths
n = actual depth/ apparent depth
Definition
Critical Angle
The angle of incidence in the optically dense medium for which the angle of refraction in the optically less dense medium is 90°.
Conditions
Total Internal Reflection
- Light ray must travel from an optically denser medium towards an optically less dense medium.
- Angle of incidence, i must be greater than the critical angle.
Definition
Principal Axis
A line passing through the optical centre of the lens and perpendicular to the plane of the lens.
Definition
Optical Centre
The midway point between the lens surfaces on its principal axis. Rays passing through the optical centre are not deviated.
Definition
Principal Focus
The point on the principal axis to which an incident beam parallel to the principal axis converges.
Definition
Focal Length
The distance between a lens’ optical centre and principal focus.
Definition
Focal Plane
The vertical plane which passes through the principal focus and is perpendicular to the principal axis.
Images
Object at infinity
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Formula
Magnification
Height of image/ Height of object
